Some semiconductor processing tools move wafers into and out of processing chambers through a passage that extends through a processing chamber wall from an area outside the processing chamber to an interior of the processing chamber. Such passages may have a gate valve, i.e. slit valve, on an end of the passage that may open in order to allow a wafer to pass through the passage, and that may close-off and/or seal (e.g., a pressure or fluid seal) the passage such that the interior of the processing chamber is isolated from the area outside the processing chamber.